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Data analysis in cosmology requires reliable covariance matrices. Covariance matrices derived from numerical simulations often require a very large number of realizations to be accurate. When a theoretical model for the covariance matrix exists, the parameters of the model can often be fit with many fewer simulations. We write a likelihood-based method for performing such a fit. We demonstrate how a model covariance matrix can be tested by examining the appropriate $\chi^2$ distributions from simulations. We show that if model covariance has amplitude freedom, the expectation value of second moment of $\chi^2$ distribution with a wrong covariance matrix will always be larger than one using the true covariance matrix. By combining these steps together, we provide a way of producing reliable covariances without ever requiring running a large number of simulations. We demonstrate our method on two examples. First, we measure the two-point correlation function of halos from a large set of $10000$ mock halo catalogs. We build a model covariance with $2$ free parameters, which we fit using our procedure. The resulting best-fit model covariance obtained from just $100$ simulation realizations proves to be as reliable as the numerical covariance matrix built from the full $10000$ set. We also test our method on a setup where the covariance matrix is large by measuring the halo bispectrum for thousands of triangles for the same set of mocks. We build a block diagonal model covariance with $2$ free parameters as an improvement over the diagonal Gaussian covariance. Our model covariance passes the $\chi^2$ test only partially in this case, signaling that the model is insufficient even using free parameters, but significantly improves over the Gaussian one., Comment: Accepted for publication in JCAP. 24 pages, 8 figures

Background Body representation disturbances in body schema (i.e. unconscious sensorimotor body representations for action) have been frequently reported in eating disorders. Recently, it has been proposed that body schema relies on adequate functioning of the motor system, which is strongly implicated in discriminating between one's own and someone else's body. The present study aimed to investigate the motor-based bodily self in eating disorders and controls, in order to examine the role of the motor system in body representation disturbances at the body schema level. Method Female outpatients diagnosed with eating disorders (N = 15), and healthy controls (N = 18) underwent a hand laterality task, in which their own (self-stimuli) and someone else's hands (other-stimuli) were displayed at different orientations. Participants had to mentally rotate their own hand in order to provide a laterality judgement. Group differences in motor-based bodily self-recognition-i.e. whether a general advantage occurred when implicitly processing self- vs. other-stimuli - were evaluated, by analyzing response times and accuracy by means of mixed ANOVAs. Results Patients with eating disorders did not show a temporal advantage when mentally rotating self-stimuli compared to other-stimuli, as opposed to controls (F(1, 31) = 5.6, p = 0.02; eating disorders-other = 1092 ±256 msec, eating disorders-self = 1097±254 msec; healthy controls-other = 1239±233 msec, healthy controls -self = 1192±232 msec). Conclusion This study provides initial indication that high-level motor functions might be compromised as part of body schema disturbances in eating disorders. Further larger investigations are required to test motor system abnormalities in the context of body schema disturbance in eating disorders.

Helicobacter pylori eradication therapy is commonly prescribed in the general population. Treatment consists of drugs that are mainly metabolized by the liver cytochrome P-450 (CYP) enzymatic pool. Most H. pylori-infected patients often take drugs for comorbid illnesses, therefore increasing the potential for drug-drug interactions. We aimed to evaluate the interactions of rabeprazole, clarithromycin, and metronidazole 1-week H. pylori eradication therapy with CYP-dependent liver metabolic function in clinical practice. Ten patients referred to our unit for H. pylori infection underwent 1-week eradication therapy with rabeprazole (20 mg, b.i.d.), clarithromycin (500 mg, b.i.d.), and metronidazole (500 mg, b.i.d.). We chose the 13C-aminopyrine breath test (13C-ABT) to evaluate CYP-dependent liver function since it is noninvasive and nonharmful. All patients underwent 13C-ABT at three time points: before therapy (to), at the end of therapy (t8), and after 1 month of follow-up (t38). Mean 13C-ABT dose/hr (t0 = 14.0 +/- 5.4, t8 = 13.5 +/- 4.0, t38 = 16.1 +/- 5.6) as well as 13C-ABT cumulative dose (t0 = 2.4 +/- 1.1, t8 = 2.4 +/- 0.8, t38 = 2.6 +/- 1.0) were not statistically different at the three time points of the study. These results did not seem to be influenced by drugs being administered concomitantly. In everyday clinical practice rabeprazole-based H. pylori eradication therapy does not seem to display any significant interactions with CYP-dependent liver function, even in patients on multiple drugs.

Background & Aims: Liver biopsy examination is the gold standard to diagnose the presence of cirrhosis. The aim of this study was to evaluate the accuracy of both 13C-aminopyrine breath test (13C-ABT) and 13C-galactose breath test (13C-GBT) in the noninvasive assessment of the presence of cirrhosis in patients with chronic liver disease. Methods: We evaluated 61 patients with chronic liver disease of diverse etiologies (21 compensated cirrhosis). All patients underwent 13C-GBT and 13C-ABT, and the results were expressed as a percentage of the administered dose of 13C recovered per hour (%dose/h) and as the cumulative percentage of administered dose of 13C recovered over time (%dose cumulative). Results were analyzed according to absence vs presence of cirrhosis. Results: On average, 13C-GBT %dose/h and %dose cumulative were decreased significantly in patients with compensated cirrhosis, and the same finding was observed for 13C-ABT results from 30 to 120 minutes. 13C-GBT %dose/h at 120 minutes had 71.4% sensitivity, 85.0% specificity, and 83.7% accuracy, whereas 13C-ABT %dose cumulative at 30 minutes had 85.7% sensitivity, 67.5% specificity, and 77.1% accuracy for distinguishing between the 2 subgroups of patients. Combined assessment of 13C-GBT and 13C-ABT increased the diagnostic accuracy (80% positive predictive value) of either test alone and reached 92.5% specificity and 100% sensitivity for the diagnosis of cirrhosis. Conclusions: In patients with chronic liver disease, both 13C-GBT and 13C-ABT are useful for the diagnosis of cirrhosis. Combination of the tests increases the diagnostic yield of each test alone.

Summary Background: Trans-catheter arterial chemoembolisation (TACE) is the most common palliative treatment for hepatocellular carcinoma (HCC). The therapeutic options depend both on the characteristics of the tumour and on functional staging of the cirrhosis. Aim: To evaluate the effects of TACE on the survival of cirrhotic patients with HCC according to different staging systems [Okuda score, Cancer Liver Italian Program (CLIP) score, Model for End-stage Liver Disease (MELD) score] and in relation to the side-effects of TACE. Methods: Fifty cirrhotic patients, 36 CTP class A and 14 class B, underwent 106 TACE treatments with mitoxantrone. Survival at 12, 24, and 36 months was evaluated. Results: MELD at 12 months and CLIP at 24 months were identified as significant variables associated with survival. Combined cut-offs of CLIP and of MELD identified four subgroups of patients with different survivals, at 12, 24 and 36 months, respectively: CLIP ≥ 2 and MELD ≥ 10 (63%, 20% and 0%), CLIP

Thrombocytopenia can be found in patients with chronic hepatitis related to hepatitis C virus (HCV). Both hypersplenism and decreased liver production of thrombopoietin (TPO) have been hypothesized as mechanisms responsible for thrombocytopenia.To assess the presence of relationships among platelet count, spleen size, TPO serum levels, liver histology, and liver function in a group of patients with HCV-related chronic hepatitis.Platelet count, TPO serum levels, and spleen size were assessed in 25 untreated HCV positive chronic hepatitis patients undergoing liver biopsy. These parameters were correlated to liver histology and liver function as evaluated by means of [(13)C]aminopyrine breath test (ABT).Both platelet counts (146 +/- 48 vs. 202 +/- 56 x 10(9)/1, P0.03) and TPO serum levels (103 +/- 24 vs. 158 +/- 7 1 pg/ml, P0.02) were lower among patients with high fibrosis scores as compared to patients with low fibrosis scores. Patients with thrombocytopenia as well as patients with high fibrosis scores had lower ABT results as compared to patients with normal platelet counts and patients with no or mild fibrosis, respectively. TPO serum levels were correlated to platelet count (r(s) = 0.493, P = 0.016), and negatively correlated to fibrosis stage (r(s) = -0.545, P = 0.008). Lastly, low TPO serum levels were associated to a decrease in liver function.Our study showed that in patients with chronic hepatitis related to HCV infection serum TPO levels are correlated to liver functional impairment and to the degree of liver fibrosis.

Background: There are few data on the use of the 13C-aminopyrine breath test to evaluate the severity of disease in patients with hepatitis C virus-related chronic liver disease, although these patients represent one of the most important problems in clinical hepatology. Aims: To compare 13C-aminopyrine breath test results of patients with hepatitis C virus-related chronic hepatitis and Child–Pugh class A cirrhosis with those of normal subjects, and to evaluate different methods of expressing 13C-aminopyrine breath test results. Methods: Twenty-four patients with hepatitis C virus-related chronic hepatitis and 17 patients with Child–Pugh class A cirrhosis underwent 13C-aminopyrine breath test. Breath samples were collected every 30 min up to 2 h after 13C-aminopyrine administration. 13C-Aminopyrine breath test results were expressed as a percentage of the administered dose of 13C recovered per hour (% dose/h) and the cumulative percentage of administered dose of 13C recovered over time (% dose cum). Nineteen healthy subjects served as controls. Patients with hepatitis C virus-related chronic hepatitis were divided into subgroups on the basis of histological staging and grading. Results: The 13C-aminopyrine breath test result (% dose/h) at 30 min was significantly different among the three subgroups of subjects (normal subjects, 11.5 ± 3.5; chronic hepatitis patients, 8.1 ± 4.1; cirrhosis patients, 5.0 ± 3.1; P 2) fibrosis scores to be distinguished. The 13C-aminopyrine breath test results (% dose cum) at 30, 60 and 90 min allowed discrimination between normal subjects and chronic hepatitis and cirrhosis patients. The 13C-aminopyrine breath test result (% dose cum) was also able to distinguish between normal subjects and chronic hepatitis patients with high but not low fibrosis scores. Both 13C-aminopyrine breath test results (% dose/h and % dose cum) at 120 min allowed the differentiation between normal subjects and chronic hepatitis patients with high (≥ 6) necro-inflammatory activity. Conclusions: In patients with hepatitis C virus-related chronic liver disease, the 13C-aminopyrine breath test proved to be safe and easy to perform, and was able to evaluate different degrees of liver function impairment which were partly correlated to clinical and histological evaluation. In future studies, 13C-aminopyrine breath test results should be expressed in a standardized fashion to permit comparison.

Background: Helicobacter pylori gastric infection has been associated with various digestive and extra-digestive diseases. The systemic influence of gastric H. pylori infection seems to be mediated by the release of various cytokines. In liver disease, bacterial infections have been associated with the impairment of liver metabolic function. Aims: To evaluate the influence of H. pylori infection on liver function as assessed by means of the monoethylglycinexylidide test, which depends upon liver blood flow and cytochrome P-450 activity, and the 13C-galactose breath test, which depends on cytosolic enzymatic activity and is correlated with hepatic functional mass. Moreover, to evaluate whether H. pylori-associated modifications of liver function may be related to tumour necrosis factor-α serum levels. Patients and methods: Thirty-five patients with liver cirrhosis of various aetiologies, who underwent monoethylglycinexylidide and 13C-galactose breath tests, were retrospectively evaluated for H. pylori infection by means of anti-H. pylori immunoglobulin G. The main clinical, biochemical and functional characteristics of the patients as well as their tumour necrosis factor-α serum levels were then analysed on the basis of the presence of H. pylori infection. Results: Twenty-one patients tested positive for H. pylori infection (60%), and 11 tested negative (31.4%). No clinical or biochemical differences were observed between H. pylori-infected and non-infected patients. H. pylori infection showed no difference in distribution according to Child–Pugh classes (A, 55%; B and C, 67%). The monoethylglycinexylidide test results were significantly lower at each sampling time in H. pylori-positive patients compared to H. pylori-negative patients (MEGX15, P=0.027; MEGX30, P=0.014; MEGX60, P=0.028), while 13C-galactose breath test showed no significant differences considering both cumulative percentage dose and percentage dose/h. The median tumour necrosis factor-α serum levels were no different between H. pylori-positive (16.1 pg/mL, 95% confidence interval, 8.7–28.7) and H. pylori-negative (12.3 pg/mL, 95% confidence interval, 8.7–23.4) patients. Conclusions: In cirrhotic patients, H. pylori infection seems to selectively affect cytochrome P-450 liver activity, while hepatic functional mass does not seem to be impaired. Tumour necrosis factor-α does not seem to be the mediator of this impairment. Further studies are needed to evaluate the impact of H. pylori eradication on parameters of liver function.

Liver biopsy examination is the gold standard to diagnose the presence of cirrhosis. The aim of this study was to evaluate the accuracy of both 13 C-aminopyrine breath test ( 13 C-ABT) and 13 C-galactose breath test ( 13 C-GBT) in the noninvasive assessment of the presence of cirrhosis in patients with chronic liver disease.We evaluated 61 patients with chronic liver disease of diverse etiologies (21 compensated cirrhosis). All patients underwent 13 C-GBT and 13 C-ABT, and the results were expressed as a percentage of the administered dose of 13 C recovered per hour (%dose/h) and as the cumulative percentage of administered dose of 13 C recovered over time (%dose cumulative). Results were analyzed according to absence vs presence of cirrhosis.On average, 13 C-GBT %dose/h and %dose cumulative were decreased significantly in patients with compensated cirrhosis, and the same finding was observed for 13 C-ABT results from 30 to 120 minutes. 13 C-GBT %dose/h at 120 minutes had 71.4% sensitivity, 85.0% specificity, and 83.7% accuracy, whereas 13 C-ABT %dose cumulative at 30 minutes had 85.7% sensitivity, 67.5% specificity, and 77.1% accuracy for distinguishing between the 2 subgroups of patients. Combined assessment of 13 C-GBT and 13 C-ABT increased the diagnostic accuracy (80% positive predictive value) of either test alone and reached 92.5% specificity and 100% sensitivity for the diagnosis of cirrhosis.In patients with chronic liver disease, both 13 C-GBT and 13 C-ABT are useful for the diagnosis of cirrhosis. Combination of the tests increases the diagnostic yield of each test alone.

Background: The model for end-stage liver disease (MELD) score is a useful tool to assess prognosis in critically ill cirrhotic patients. However, its short-term prognostic superiority over the traditional Child–Turcotte–Pugh (CTP) score has not been definitely confirmed. The creatinine serum level is an important predictor of survival in patients with liver cirrhosis. Aims: To evaluate and compare the short-term prognostic accuracy of the CTP, the creatinine-modified CTP, and the MELD scores in patients with liver cirrhosis. Methods: CTP, creatinine-modified CTP, and MELD scores were calculated in a cohort of 145 cirrhotic patients. The creatinine-modified CTP was calculated as follows: we assessed the mean creatinine serum level and standard deviation (SD) of the 145 study patients, then assigned a score of 1 to patients with creatinine serum levels ≤ to the mean, a score of 2 to patients with creatinine levels between the mean and the mean+1 SD, and a score of 3 to patients with creatinine levels above the mean+1 SD. The creatinine-modified CTP was then calculated by simply adding each patients' creatinine score to their traditional CTP scores. We calculated and compared the accuracy (c-index) of the three parameters in predicting 3-month survival. Results: The creatinine-modified CTP score showed better prognostic accuracy as compared with the traditional CTP (P=0.049). However, the MELD score proved to be better at defining patients' prognosis in the short-term as compared with both the traditional CTP score (P=0.012) and the creatinine-modified CTP (P=0.047). The excellent short-term prognostic accuracy of the MELD score was confirmed even when patients with abnormal creatinine serum levels were excluded from the analysis (c-index=0.935). Conclusions: Adding creatinine values to the CTP slightly improves the prognostic usefulness of the traditional CTP score alone. The MELD score has a short-term prognostic yield that is better than what is provided by both the CTP and CTP creatinine-modified scores, even in cirrhotic patients who are not critically ill. The positive results obtained by using the MELD score were confirmed even after excluding patients with impaired renal function.

Lansoprazole (LAN) is a proton pump inhibitor drug (PPI) metabolized by the P-450 liver cytochrome (CYP-450) system. LAN is used in association with antimicrobial agents in Helicobacter pylori (HP) eradication therapy. The 13C-Aminopyrine breath test (ABT) is a non-invasive tool exploring liver CYP-450 metabolic activity. Since pharmacological interactions may occur during PPI administration, we attempted to evaluate possible interference with liver CYP-450 activity during HP eradication therapy.Fourteen HP positive patients received LAN (30 mg b.i.d.), clarithromycin (500 mg b.i.d.) and metronidazole (500 mg b.i.d.) for one week. Prior to therapy, and at day 8, each patient underwent 13C-ABT. The 13CO2 concentration in breath samples was measured every 15 minutes from t0 to t120. Results are expressed as cumulative percentage of the administered dose of 13C recovered over time (% 13C dose cum), and as a percentage of the administered dose of 13C recovered per hour (% l3C dose/h). Comparisons were carried out by the Wilcoxon test. Data are presented as mean +/- SD.At day 8, mean ABT was no different from baseline values, both considering % 13C dose cum and% 13C dose/h at each sampling time (e.g.,% 13C dose cum120 which is the most expressive value of the parameters taken into consideration, baseline vs day 8: 10.88 +/- 3.81 vs 10.13 +/- 3.57).These results show that LAN administration and the concomitant use of antimicrobial drugs during HP eradication therapy do not seem to be associated with significant modifications in liver CYP-450 activity.

Background. Epidemiological studies have foreseen an increase in the incidence of hepatocellular carcinoma (HCC) in the near future and it is estimated that this trend will mostly affect hepatitis C virus (HCV) positive cirrhotic patients. Therefore, accuracy of HCC staging is an important clinical issue. Aim. To investigate the prognostic usefulness of a series of newly proposed HCC prognostic systems such as the Cancer of the Liver Italian Program (CLIP) score, the Groupe d'Etude et de Traitement du Carcinome Hepatocellulaire (GRETCH) model and the Barcelona Clinic Liver Cancer (BCLC) staging classification when compared with the usefulness of a known staging system such as the Okuda staging system in a group of anti-HCV positive cirrhotic patients with HCC seen at a single centre. Methods. Okuda stage, CLIP score, GRETCH model and BCLC stages were retrospectively computed in 81 anti-HCV positive cirrhotic patients with HCC. We evaluated and compared the ability of these methods to assess survival prognosis. Results. As of December 2001, 51 patients had died and overall median survival was 18 months. All the staging systems were able to identify various patient subgroups with different survival. The CLIP score, the GRETCH model and the BCLC staging classification were better at characterizing the 1-year prognosis of the patients when compared with the Okuda staging system, whilst the 3-year prognostic evaluation was improved only by using the CLIP score or the BCLC staging classification. Conclusions. The prognostic value and usefulness of the CLIP score, the GRETCH model and the BCLC staging classification was reproduced in a single-centre analysis of anti-HCV positive HCC cirrhotic patients. These scores provided a prognostic assessment of our patients which is superior to what was obtained by the Okuda staging system.

Thrombopoietin (Tpo) is an important regulator of megakaryocyte maturation and platelet production, and is mainly produced by the liver. A decrease in Tpo production is partly responsible for the thrombocytopenia observed in patients with chronic liver disease (CLD). The aim of this study was to evaluate the relationship between Tpo serum levels and liver function in patients with CLD related to hepatitis C virus (HCV) infection.We studied 37 patients with various degrees of HCV-related CLD. Of the patients, 17 had chronic hepatitis and 20 liver cirrhosis. Liver function was evaluated in all patients by the following hepatic blood flow dependent and independent tests that explore various hepatic metabolic functions: carbon-13 (13C)-aminopyrine breath test (13C-ABT), 13C-galactose breath test (13C-GBT), and monoethylglycinexylidide (MEGX) test. Liver function tests results were correlated with Tpo serum levels.Tpo serum levels were significantly lower in patients with liver cirrhosis (88 +/- 23 pg/ml) as compared to those in patients with chronic hepatitis (128 +/- 55 pg/ml, p=0.0031). However, they did not correlate with serum albumin, bilirubin, or prothrombin activity. Tpo serum levels showed a significant positive correlation with 13C-ABT results (hourly dose at 30 min, rs=0.489, p=0.002; cumulative dose at 120 min, rs=0.425, p=0.008). Moreover, they showed a fair, positive correlation with 13C-GBT hourly dose at 30 min (rs=0.366, p=0.028), and a trend toward a positive correlation with the various MEGX test sampling times (MEGX15, rs=0.314, p=0.059; MEGX30, rs=0.284, p=0.088; and MEGX60, rs=0.320, p=0.059).In this study we have shown that a progressive decline in liver function in patients with HCV-related CLD is paralleled by a decrease in Tpo production. The different correlations observed between Tpo and the various liver function tests suggests that this finding is mainly the result of a decrease in hepatic functional mass rather than dependent on alteration in splanchnic hemodynamic.

Interferon is considered the cornerstone in the therapy of chronic hepatitis C patients. Experimental studies have shown that interferon administration may influence liver metabolic activity. However, data concerning the monitoring of liver metabolic function during a therapeutic course of interferon in chronic hepatitis C patients are scanty. The MEGX (monoethylglycinexylidide) test has been used in diagnostic and prognostic assessment of chronic liver disease as a quantitative liver function test. In this study our aim was to non-invasively monitor liver function in chronic hepatitis C patients during a course of interferon-alpha therapy and to evaluate whether the presence of modifications in liver metabolic function might influence the therapeutic outcome.We studied 22 patients with biopsy-proven chronic hepatitis C before, during (1st, 3rd and 6th month of therapy), and three months after interferon-alpha (3 million units thrice weekly for six months) using MEGX test to monitor liver function.During the longitudinal study no significant differences were observed between pretreatment MEGX30 values and those obtained during interferon treatment or at the end of follow-up, both considering patients together or grouped according to treatment outcome (Responders vs. Non-responders). Analysis of the MEGX30 variations during therapy showed that they were evenly distributed between responder and non-responder patients. Furthermore, during interferon therapy none of the patients reached a MEGX30 value compatible with severely impaired liver function.Our results suggest that although a discrete prevalence of modifications in liver metabolic function occurs in chronic hepatitis C patients during interferon therapy they do not seem to have clinical relevance or influence therapeutic outcome.

OBJECTIVES: The AST/ALT ratio has shown good diagnostic accuracy in patients with chronic viral liver disease. However, its prognostic utility has never been tested. Recently, the Model for End-Stage Liver Disease (MELD) has been proposed as a simple and effective tool to predict survival in patients with liver cirrhosis. The aims of this study were to assess the 3-month and 1-yr prognostic ability of the AST/ALT ratio in a series of patients with virus-related liver cirrhosis, and to evaluate the relationship between the AST/ALT ratio and the MELD score and to compare their prognostic ability. METHODS: The AST/ALT ratios and MELD scores of 99 patients with liver cirrhosis of viral etiology (73 patients with hepatitis C virus and 26 with hepatitis B virus) who had been followed-up for at least 1 yr were retrospectively calculated and correlated with the patients’ 3-month and 1-yr prognosis. Receiver operating characteristic curves were used to determine the AST/ALT ratio and the MELD score cut-offs with the best sensitivity (SS) and specificity (SP) in discriminating between patients who survived and those who died. Univariate survival curves were estimated by the Kaplan-Meier method using the cut-offs identified by means of receiver operating characteristic curves. RESULTS: AST/ALT ratios and MELD scores showed a significant correlation (rs = 0.503, p = 0.0001). In all, 8% and 30% of the patients had died after 3 months and 1 yr of follow-up, respectively. AST/ALT ratios and MELD scores were significantly higher among the patients who died during both 3-month and 1-yr follow-up. An AST/ALT ratio cut-off of 1.17 had 87% SS and 52% SP, whereas a MELD cut-off of 9 had 57% SS and 74% SP in discriminating between patients who survived and those who died after 1 yr. The combined assessment of the AST/ALT ratio and/or MELD score had 90% SS and 78% SP. Survival curves of the patients showed that both parameters clearly discriminated between patients who survived and those who died in the short term (AST/ALT ratio, p = 0.0094; MELD score, p = 0.0089) as well as in the long term (AST/ALT ratio, p < 0.0005; MELD score, p = 0.004). CONCLUSIONS: In patients with virus-related cirrhosis, the AST/ALT ratio has prognostic capability that is not significantly different from that of an established prognostic score such as MELD. Combined assessment of the two parameters increases the medium-term prognostic accuracy.